This invention relates to the recovery of bituminous oil from tar sands. More specifically, the invention relates to a surfactant aided recovery of bituminous oils from oil wet tar sands, specifically from oil wet acidic tar sands.
Many processes have been described in the prior art to separate hydrocarbons from sands containing such hydrocarbons. One class of separation processes involves the use of hydrocarbon solvents. More specifically, many processes have been described in which hydrocarbon extraction of bituminous oil containing sands under high temperature conditions is utilized. In such processes the specific problem of solvent losses with the sand arises.
Other processes can be characterized as water extraction processes. Both hot and cold water has been described for separating hydrocarbons from sands. A typical example of the prior art process is described in U.S. Pat. No. 3,875.046. There a countercurrently flowing bed of tar sands is contacted with steam, solvent and recycle water to establish an aqueous layer and an oil solvent layer on top of the sand bed. The sand in this process is subjected to extraction by the fluids described in the form of a down flowing sand bed which is only gently fluidized. A fluidization of this bed is intentionally gentle to avoid any removal of sand fines and clay from the sand particles. U.S. Pat. No. 3,875,046 also describes wetting agents, dispersing agents, flocculants, pH control agents to be introduced optionally into the water system.
A continuing need exists for new and improved processes for the recovery of bitumen oil from tar sands. Since most prior art processes have been described in connection with Athabasca sands, i.e. sands which are not oil wet, a need exists for efficient processes for recovering oil from oil wet tar sands that are strongly acidic.